Consider the burger, our edible Zelig, fast food staple, and bistro standard, at ease on the farm table or the Formica counter, comfortable matched with a milkshake or a merlot. In San Francisco, the adaptability of ground beef on a bun is evident in burgers of boundless iterations, from the spendy corporate burger ($25 for a Morbier-stuffed half-pounder at Epic Roasthouse) to the fashionable fast-food burger ($6.50 for Super Duper’s upgrade of In-N-Out).

Tastes run high and tastes run low, but the burger most reflective of this culinary moment is the one that borrows from both ends of the spectrum; the burger of fine pedigree but clinging to its street cred—the middle-brow burger. And KronnerBurger makes among the best in town.

The venture is the latest from chef Chris Kronner, who cooked at Slow Club, Serpentine, and, most notably, Bar Tartine. His burger was so popular that it inspired a popup that now appears to have found a stable home. For the “indefinite future,” Kronner says, he plans to make a go of it at Bruno’s, the landmark Mission club and restaurant where other pop-ups have come and gone.

From the outside, the place looks practically condemned. In a dark window, a small television displays the restaurant’s name in flickering graphics. It’s the only sign of life within.

But life inside there is—life of an underground but welcoming variety, like the kind you’d find at a friendly vampire bar. Kronner has annexed Bruno’s overflow space, which the club uses on Saturday nights, the only night that KronnerBurger is closed. The room is long and narrow, with a bar in back and candles glimmering on uncovered tables. Poppy punk tunes serve as soundtrack for a scene that is very much the youthful Mission, all skinny jeans and plaids and beards and piercings. KronnerBurger is a secret that has gotten out.

The menu, printed on paper place mats, has some items that come and go. You might find a burger made with sweetbreads or a meaty Dungeness crab burger, crowned with dill-pickle tartar sauce with fennel. But its unchanging centerpiece—and the item almost everybody orders—is the Kronnerburger, offered as a single or a double. Four bucks gets you marrow on the side.

It bears saying that just because it’s easy to ruin a burger (overcook it; pour Heinz ketchup on it) doesn’t mean that it’s hard to make a great one. Aficionados fuss over the burning questions: the right mix of toppings, say, or the proper ratio of beef to bun. But beyond that, there’s really not much to it. Delve any deeper into obscure inquiries (the weight of the patty; the nuance of its umami char), and you’ve left behind the world of the burger expert to enter the realm of the fetishist. (I’ll leave you there to chat with your strange kin.)

Kronner, however, keeps things simple: His patties, made of medium-rare grass-fed beef, are presented on toasted Acme pain de mie and garnished with iceberg lettuce, homemade pickles, roasted red onions, and cheddar mayo. (If you prefer your burger without much sauce, get the mayo on the side.) The combination yields an appealing balance of sweet and salty, bright and fatty. Odds are that you’ll wind up licking your fingers for the plentiful beef juices, which run with just a trace of blood.

The menu also features a “notmeatburger” made with lentils, beets, and chickpeas and served on a bun smeared with wild nettle “ketchup.” It is rich enough that a vegetarian won’t feel cheated, though the oils that it absorbs give it too much ballast for my taste. A patty melt is another mainstay. Though smothered in cheese and caramelized onions and spiked with horseradish mustard, the patty itself is a bit thin and dry.

The burger is the clear star here, and it benefits from its supporting cast. Among the standout sides are fries bathed in cheese curds and beef cheek gravy, an addictive poutine spin-off. The onion rings, too, are pretty much perfect, their sweetness sealed in a crackling coating. As he did at Bar Tartine, Kronner erects a Stonehenge of marrow bones landscaped with refreshing parsley salad. And he serves what is the finest iceberg wedge I’ve had, with a scattering of herbs, a biting blue-cheese dressing, and hunks of smoky pork belly that nearly make the salad a meal unto itself.

Everything on the menu, right down to the black banana bread pudding—a decadent dessert doubled up with dulce de leche sauce and dark chocolate ice cream—tilts toward a masculine aesthetic that at times mutates into juvenile machismo. For example, a cocktail called a “carbonated motherfucking margarita” makes you wonder whom Kronner is trying to impress.

At its core, however, KronnerBurger is more mature than that, with grown-up service and a seasoned chef who has dreamed up a fine concept for the Mission district. It’s easy to imagine him staying at Bruno’s, but Kronner says that he’s looking to replicate the model, maybe in Oakland. That isn’t difficult to picture. Like the clientele it serves, KronnerBurger only looks as if it’s living in suspended adolescence. Truth is, it’s ready to reproduce.